[OZAPRS] Why we don't always make it...
Terry Neumann
tfneumann at internode.on.net
Sat Feb 18 12:21:59 EST 2012
On 17/02/2012 8:21 AM, ozaprs-request at aprs.net.au wrote:
> Message: 1
> Date: Thu, 16 Feb 2012 19:46:28 +1100
> From: "Nic McLean"<mcleannb at bigpond.com>
> To:<ozaprs at aprs.net.au>
> Subject: [OZAPRS] No recent positions on Googlemaps.
> Message-ID:<000001ccec87$7bb3e8f0$731bbad0$@bigpond.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi,
>
> Does anyone on the list know why aprs positions aren't making it from RF to
> googlemaps?
>
> Best 73's
>
> Nic
>
> VK5ZAT
G'day Nic,
Additional to what Tony has already offered, there can be other reasons
why we sometimes won't be seen on APRS servers,
1) The path you set for your packets may not be "sufficient" to survive
the number of hops needed to make it to an Igate. Check up that you
have this correctly according to the published recommendations.
2) Congestion on the frequency can be a real issue in my observation /
experience, especially if there are a large number of (fixed) stations
transmitting information. I am sometimes quite surprised at how much
of this there is - at least from my QTH. In the midst of all of this
your beacons may simply be swamped by some of this traffic especially
if, as a mobile station running (probably) lower power and the
constraints of mobile antennas, you are competing with all the
advantages of base stations in locations with a large spread. The
'hidden transmitter" issue present right from the early days of packet
radio is nearly always with us. Throw in random geographical barriers
and it all becomes a game of chance.
I know in my own travels it's not uncommon to be "un-noticed" by the
system in my trips around this area if I haven't turned my own
digipeater on - even when one might expect otherwise. I only run 5
watts in the car and I know that sometimes I can drive for 25 or 30
minutes through locations where one would expect to 'make it' and miss
out altogether until I come within the range of my own or some other
digi where I acquire a certain RF priority.
As Tony says, given all of these challenges, it's amazing that the
system works as well as it does.
73
Terry
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